FIG. 11A is a view showing a conventional example of an analog switch of CMOS [Complementary Metal Oxide Semiconductor] type, and FIG. 11B is a view showing an electrical drawing symbol of an analog switch ASW. The present conventional analog switch ASW has a MOS field effect transistor N of N channel type and a MOS field effect transistor P of P channel type that are connected in parallel with each other, and electrically connect/disconnect an application terminal for an input voltage Vin and an application terminal for an output voltage Vout in accordance with a control voltage Vctrl (+) and an inverting control voltage Vctrl (−) applied to their respective gates.
Sources of the transistors N and P correspond to a first terminal of the analog switch ASW, and are connected to the application terminal for the input voltage Vin. Drains of the transistors N and P correspond to a second terminal of the analog switch ASW, and are connected to the application terminal for the output voltage Vout. A gate of the transistor N corresponds to a control terminal of the analog switch ASW, and is connected to an application terminal for the control voltage Vctrl (+). A gate of the transistor P corresponds to an inverting control terminal of the analog switch ASW, and is connected to an application terminal for the inverting control voltage Vctrl (−). A back gate of the transistor N is connected to an application terminal for a ground voltage GND. A back gate of the transistor P is connected to an application terminal for a power supply voltage VDD.
In a case where the analog switch ASW is turned on, the control voltage Vctrl (+) is brought to a high level (power supply voltage VDD), while the inverting control voltage Vctrl (−) is brought to a low level (ground voltage GND). By the application of these voltages, at least one of the transistors P and N is turned on, and the application terminal for the input voltage Vin and the application terminal for the output voltage Vout are electrically connected to each other.
On the other hand, in a case where the analog switch ASW is turned off, the control voltage Vctrl (+) is brought to a low level (ground voltage GND), while the inverting control voltage Vctrl (−) is brought to a high level (power supply voltage VDD). By the application of these voltages, both transistors P and N are turned off, and the application terminal for the input voltage Vin and the application terminal for the output voltage Vout are electrically disconnected from each other.